The present invention relates to a spring system of a rail vehicle with at least one spring strut for arrangement between bogie and carriage body of the rail vehicle. The spring strut includes at least one cylinder and at least one piston shiftably accommodated in the cylinder, which define piston spaces below and above the piston head. The piston or the cylinder is directly or indirectly connectable or connected with the bogie, and the other one of the components is directly or indirectly connectable or connected with the carriage body, and with at least one spring which is arranged such that the same cushions the carriage body with respect to the bogie.
Such a spring system is known from German document DE 10 2006 027 288 A1. The spring system disclosed there comprises a non-resilient hydraulic system which is connected with the piston space and by means of which the quantity of the hydraulic medium in the piston space is variable for the purpose of adjustment of the spring strut length. Furthermore, there is provided a stop element by means of which the end position of the piston in the cylinder is variable. This stop element is actuated when in a case of fault the piston space or the hydraulic system is pressureless or the pressure falls below a certain value.
In this known spring system a special emergency system is activated upon failure of the hydraulic system, so that no operational constraints must be accepted. The same include for example a reduced speed, a reduced number of passengers as well as putting the rail vehicle out of operation.
Typical spring systems are furthermore known from German document DE 103 15 000 A1 and U.S. Pat. Nos. 7,185,592 B2, 7,243,606 B2 and 7,874,254 B2.
In German document DE 103 15 000 A1 a secondary spring system of a rail vehicle is disclosed, wherein between a bogie and a carriage body a spring stage is arranged. The spring stage includes a passive steel spring and an actuator. When the actuator is released, the steel spring effects that the carriage body is lifted into a driving position. During stoppage in a railway station, the actuator pulls the carriage body in direction of the subframe against the restoring force caused by the steel spring. The actuator can be a hydraulic actuator.
U.S. Pat. No. 7,185,592B2 discloses a development of the system shown in DE 103 15 000 A1. There is presented a special hydraulic system for the actuator, which comprises a hydropneumatic accumulator and depressurizes the actuator when the carriage body is lifted.
U.S. Pat. No. 7,243,606 B2 discloses an alternative solution of a generic system, in which the secondary spring system includes a hydropneumatic spring unit.
U.S. Pat. No. 7,874,254 B2 discloses a further solution of a generic system, in which a special construction of the piston rod is provided.